Mr Fahmi faces another charge under Section 233(1)(a) of the Communications and Multimedia Act 1998 in the state of Perak on Friday.

Section 233(1)(a) prohibits the use of network facilities or network service to "comment, request, suggestion or other communication which is obscene, indecent, false, menacing or offensive in character with intent to annoy, abuse, threaten or harass another person".

If convicted, he could face up to one year in jail and/or a RM50, 000 (US$12,200) fine.

Mr Fahmi first posted the clown image in January 2016, commenting on corruption and how frequently the controversial Sedition Act was used in Malaysia "to charge Malaysians brave enough to rise up and speak".

The photo was accompanied by the hashtag #KitaSemuaPenghasut or #WeAreAllSeditious.

After Malaysian police informed Mr Fahmi his postings were being monitored, art collective Grupa and Malaysians began spreading the image and the #KitaSemuaPenghasut visual protest was born.

The artist and three others were detained for questioning on Saturday at an arts event where they had been selling t-shirts bearing the image of Mr Najib as a clown.

Mr Najib has come under fire in the past year over allegations of corruption. Reports alleged investigators believed some US$700 million had been channelled into his personal bank accounts ahead of the 2013 general elections through entities linked to troubled state investment firm 1MDB - which was advised by Mr Najib.

However, Malaysia's Attorney-General closed investigations into the Prime Minister earlier this year, saying he found no evidence of wrongdoing.

He also confirmed Mr Najib's assertion that the money was a political donation from the Saudi royal family.